According to research firm Gartner, 80% of social business efforts will fail through 2015- a disconcerting statistic for the 50% of all large businesses expected to deploy social networks in the next three years.

A few of the reasons for the failures, according to Gartner Research Director Larry Cannell: adoption and ROI expectations and a lack of executive support, he says.

"Too many people just assume that an enterprise social network [ESN] deployment is going to be simple and that people will pick it up quickly," Cannel says. "And that's just not the case. Social is different from any other project you may have deployed, and you need to put in place certain measures to be successful."

Here's a look at the three most-common enterprise social network mistakes and what you need to do to avoid making them.

1. Don't Assume Adoption Will Grow Organically

"Just because an enterprise social network is simple and easy to use doesn't mean you can build them and people will come," Cannell says. "These tools are going to change how people work and you need to prepare them for that."

In the early planning stages, Cannell says, you need to determine how people are currently working and how an ESN will change that.

"Partner with business leaders to understand what their jobs are," Cannell says. "What information do they need to do their jobs? Who do they work with?"

Then, define clear reasons why employees will benefit from such a drastic-and sometimes uncomfortable-change in process.

"It's not like you can just turn on a Yammer or Chatter network and people will come. Employees need to know what they're used for and why they should care," Cannel says. "They need motivation and an understanding of why they should want to participate." A clear understanding of this, he says, is key to gaining adoption.

Another key to success is embedding the social network into everyday workflow. Managers need to ensure the tools are part of how they get their jobs done every day, Cannell says, rather than just being destination sites.

When business analytics company SAS deployed a pilot of Socialcast, it found itself in an enviable position: Adoption unexpectedly went viral as more than 1,400 employees signed up to use it.

The reasons, according to its team: Executives were excited about the project, they properly trained their employees and promoted the project heavily within the company, they made it accessible to everyone, and they trusted their employees to use it properly.

Any IT project needs to deliver ROI, but the one associated with an enterprise social network needs to be considered differently.

"Your ROI argument is tied to how you expect to deploy the software," Cannell says. "Sure, you can focus on things like how many people sign up and post, and that's OK. But if you focus on the individual deployments and making employees actually like the tool, then more relevant metrics come into play."

Some of these more difficult-to-measure metrics may include things like handling more work with fewer people, streamlining processes and spending less time on trivial things like searching an intranet for an answer to a question.

"You might not be able to anticipate what some of the most important benefits might be, but you can get the business to express them more broadly after they've gone through it," Cannell says.

At TD Bank Group, one of the most significant ROIs was realized with its deployment of an IBM solution to 50,000 users: Some business units saw a drastic reduction in email, by as much as 40 to 1, according to Wendy Arnott, TD Bank's vice president of social media and digital communications.

Gaining executive buy-in and using their participation in the enterprise social network to set an example for the rest of the company is essential to the success of the project, Cannell says. But this can be challenging.

"If you're starting small and building the system out, these projects don't usually start out as a big line on an exec's radar," he says. "But business execs need to understand the goals and support them. Senior management is key to motivating people to participate in these communities," he says.

When Mannakkara pitched the project to the executive team, he focused on it as a communication tool that would achieve better productivity. He highlighted how employees wanted to hear more from the executive team, and this was an easy way to get the job done.

"Plus, part of it is just having executives get exposure to the technology and others who have seen it work," he says. "Then they're not as afraid of the technology."